1. Field of the Invention
The present invention relates to a technique for discriminating walking and running from each other by an acceleration sensor.
2. Description of the Related Art
Methods of automatically discriminating whether a user (subject) is in a walking state or a running state by an acceleration sensor attached to the body have been being studied. A technique of this kind is applied to, for example, an apparatus for measuring a quantity of exercise (step count, energy expenditure (consumption), or the like) or an intensity of exercise (METs or the like) (pedometer, activity monitor, or the like) and an apparatus for recording/managing a physical activity of a subject in a hospital or a rehabilitation facility. (“METs” is a unit of metabolic equivalent.)
In Japanese Patent Application Laid-Open No. 7-178073, a method of extracting an AC component in an output signal of an acceleration sensor and discriminating walking and running from each other based on the frequency and amplitude of the AC component is proposed. Certainly, during running, the pitch is higher and a vertical motion of the body is larger than those during walking. Consequently, as a general tendency, the frequency of an acceleration waveform is higher and the amplitude is larger. However, since the frequency and the value of the amplitude which change from the walking state to the running state vary among individuals, in the case of a conventional uniform discriminating method, there is the possibility that the discrimination ratio markedly drops depending on a user.